Air cleaner and intake silencer assembly



Feb. 11, 1958 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23, 1954 5SheeQs-Sheet l EZE'ILZZU T5 (Joseph B. Saba t ZEa/ E. fiendelbach fiH HFeb; T1 1958 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23, 1954 5Sheets-Sheet 2 u M? N I N n 7 7 I: I I I: 1 I w" l rw J "D N N i N \\n vi we ,1 k i EYFETZZETE Joseph B. 156b71 Pa 1,012 5. sew/611142 12 Feb.11,1958 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23, 1954 5Sheets-Sheet 3 I 271 5 IZfQTS Joseph B. 565012 g 754/52 5. Sande/bashHZZLjS Feb- 11, 1 5 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23. 1954 5Sheets-Sheet 4 2 gg m Feb. 11, 1958 J. B. SEBOK ET AL 2,82 ,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY I Filed Feb. 23. 1954 5Sheets-Sheet 5 E-FE 7:2 Zn T5 i Fez/f1 5 Sendelbacfi United StatesPatent AIR CLEANER AND INTAKE SILENCER ASSEMBLY Joseph B. Sebok,Dearborn, and Ralph E. Sendelbach, Detroit, Mich., assignors, by mesneassignments, to Purolator Products, Inc., Rahway, N. J., a corporationof Delaware Application February 23, 1954, Serial No. 411,612 22 Claims.(Cl. 183-15) This invention relates to improvements in an air cleanerand intake silencer assembly, and more particularly to such an assemblyhighly desirable for use in connection with internal combustion enginesof the automotive type,

although the invention will have other uses and purposes for mechanismsrequiring an air and also desirable silencing emanating from the intake,skilled in the art.

For purposes of clarity'and adequate disclosure, the instant inventionwill be herein considered in connection with its use in association witha carburetor of an internal combustion engine, such as the commonlyknown automobile engine.

adequate supply of clean of intake noises or noises as will be apparentto one I-Ieretofore, the type of intake silencer commercially used withautomobile engines has universally been a silencer operating uponresonator principle, and wherein a casing was arranged to provide achamber of predetermined volume whch communicated with a path throughwhich sound waves might travel, but was otherwise closed.

In many cases communication was established with the resonator chamberby way of a tube concentric with but spaced from an air duct, and inother cases by way of a tubular element having apertures therein. Ofcourse, the resonator chamber was to attenuate a sound of predeterminedfrequency, this being in most cases the fundamental tone of theautomobile engine. The tuning of a resonator chamber to a particularfrequency depends upon the volume of the chamber and the charactor ofthe acoustical coupling by which communication is established with thepath traveled by the sound waves. Most frequently the resultant tuningwas accomplished by varying the size and length, or both, of the tubeestablishing communication with the chamber, and that tube wasfrequently referred to as a tuning tube. In some instances compoundresonating chambers or resonating chambers connected in serieswere'utilized,

simple expedient to provide a tuning tube for connection with thecarburetor intake horn, and terminate the clean air outlet tube insidethat tuning tube, but spaced therefrom.

However, the difficulty of providing adequate silencing for anautomobile engine has tremendously increased with the advent of higherhorsepower engines, and lower hoods on automobile, thereby limiting thespace in which attenuating chambers cated. This tendency toward lowerhoods and less space of adequate volume may be lo-' in the enginecompartment has now progressed to such an extent that in a number ofcases the air cleaner and silencer assembly must actually seat down overand house the major portion of the carburetor, the former housing whichwas an integral part of the carburetor and to which the intake horn wasattached having been eliminated. That required the central portion ofthe air cleaner, or in effect, the clean air outlet conduit, to beenlarged so that the upper part of the carburetor could be receivedinside the air cleaner-silencer assembly. In some cases, thisenlargement was up to three times the previous diameter. In manyinstances it was also desired to reduce the overall height, fromcleaners and silencers used theretofore. As a result, extreme difficultywas experienced in finding space for a resonator chamber of adequatevolume to effect the desired silencing, and increase in engine sizeusually requires a greater volume in the attenuating chamber. Evengreater difficulty has been experienced in endeavor-ing to tune such anattenuating chamber of the true resonator type to a predeterminedfrequency because of the greater chamber size, and more particularlybecause of the lack of room for an acoustical coupling to that chamberin the form of a tube which could be lengthened or shortened or variedin diameter.

Endeavors to solve that problem have resulted in complicated structuresof highly expensive character, and in many cases prohibitively expensivefor commercial production and acceptance.

The instant invention effectively and economically solves the foregoingproblems.

Inasmuch as the theory or principle of operation of the instantinvention has not as yet been fully determined, and it is not yet knownwhether or not the instant invention effects sound attenuation on theprinciple of operation of a true resonator attenuating chamber, theattenuating chamber will be herein referred to as a volume or silencingchamber, for purposes of accurate presentation, the actual efiiciencyand efiicacy of the instant invention having been conclusively proven inpractice.

With the foregoing in mind, it is an object of the instant invention toprovide a new type of silencer embodying a tuned volume chamber.

Another object of the invention resides in the provision of an aircleaner-intake silencer assembly designed for disposition over the majorportion of a carburetor, and the silencing means of which includes avolume chamber which is easily and economically tuned to a desiredfrequency.

A further object of the invention resides in the provision of a volumechamber type of silencer that can readily and economically be varied atthe time of manufacture to be eifective on several different automotiveengines, without resort to expensive die changes, or provision ofduplicate dies, or a reconstruction of the main part of the silencer.

It is also a feature of the invention to provide a volume chamber typesilencer for internal combustion engines, so constructed as to provide agreat range of tuning which may be accomplished with no change whateverin the overall dimensions of the silencer.

Another feature of the invention resides in the provision of an aircleaner-intake silencer assembly wherein the silencer involves a volumechamber, and the tuning tube for the volume chamber also functions as anair inlet to the air cleaner.

It is also a desideratum of the instant invention to provide a volumechamber type intake silencer with the tuning tube therefor located wthinthe volume chamber.

Still another object of the invention resides in the provision of an aircleaner-intake silencer assembly in which sound emanating from theinternal combustion engine or other source is passed through the filterelement of the air cleaner before reaching the volume chamber of thesilencer, thus causing the filter element of the air cleaner vision ofan air cleaner-intake silencer assembly,- inwhichthe silencer involves avolume chamber readily tunable,

and incoming air passing through-the -aircleaner also passes. throughthe volume chamber of the silencer.

,Still another object of the invention resides-inthe provision of anaircleaner-intake silencer-assembly, wherein the filter element of theair-cleaner may be separately removed, the cleansing liquid container ofthe 'air cleaner may be separately removed,-and the silencer casing leftin position.

Also-a feature of-the invention is the provision of an intake silencerof the volume chamber type wherein the overall height ofthe structure isreduced to a minimum.

While some of themore salient features, characteristics and advantagesof the instant invention'have' been above pointedout, others will becomeapparent from the following disclosures, taken in conjunction with theaccompanying drawings, in which- -Figure 1 is-abottom plan view of anair cleaner-intake silencer assembl-yembodying principles of the instantinvention;

Figure-2 is anenlarged fragmentary part central vertical sectional, partside elevational view of the structure of Fig. 1, showing the same inoperative association with the carburetor of an internal combustionengine;

Figure 3 is a'fragmentary central vertical sectional view showing aslightly. different form of construction for the assembly of Figs. 1 and2;

Figure 4 is a bottom plan view of an air cleaner-intake silencerassembly embodying principles of the instant invention but illustratinga different construction of the silencer portion;

Figure 5 is a fragmentary centralyertical.sectional view through thestructure of Fig. .4;

Figure 6 is a fragmentary central vertical sectional view through an aircleaner-intake silencer'assembly embodying a still different form ofconstruction; and

Figure '7 is a part central vcrticalsectional, part side elevationalview of a cleaner-silencer assembly embodying an extra true resonatorchamber, in addition to the volume chamber disclosed in the abovestructures- As shown on the drawings:

That illustrated embodiment of the instant invention seen in Figs. l and2 is shown operatively associated with a carburetor of the so-calleddowndraft type. This carburetor in and of itself does not.form .a partofthe instant invention and need not be of the particulapstructureillustrated. The carburetor itself includes a base portion 1 which mayhouse the usnalventuriandthrottle valve and is the portion through whichthe combustible mixture passes. On top of this base portion is anannularflange or platform 2 which functions-asp 'seat for-theair cleaner-intakesilencer assembly. The choke valve of the carburetor willusually belocated substantiallyin the plane of the flange ,2. Above that fla'ngethecarburetor includes the usual float chamber arrangement '3,vanzaccelerating pum n ement stand. .lothe parts .com;

monly utilized in-carburetors for internal combustion engines. It willbe noted that the carburetor utilizedwith the instant invention does notinclude the customary cast housing over all the upper portion thereofand which housing terminates in an air intake horn. In this instance,incoming air surrounds all the portion of the carburetor abovetthe-flange 2, and that part of :the carburetor is housed or enclosed bythe aircleaner-silencer assembly. Obviously, the carburetor may be ofthe single or dual type, depending upon the character ofengine it is'tosupply with fuel. In..Figs.;5- to 7, Ihave indicated the same type ofcarburetor in dotted lines.

The .air. cleaner-intake silencer assembly includes an outer casing orshell, preferably fabricated from separate pieces to save cost inmanufacture and including a bottomed cylindrical lower portion 5 and anupper portion 6 lock seamed or. otherwise secured to the lower portionas indicated at 7. While it'is desirable for manufacturing-economytomake asmany'casing portions of an air cleaner as possible ofcylindrical contour, in the present instance theupper portion 6 of theshell is made somewhat eccentric, to project beyond the lower portion 5at onesideof the structure,,as indicated at 8. This is done in order toincrease the volume inside the casing without adding to the height ofthat casing. The top of the upper portion 6 is provided with a circularopening 9, and adjacentthis openingthe casing is formed to provide aseat for an annular gasketlfl. A circuit opening is also provided in thebottom of the'lower section 5, and is generally defined by a dependingflange 11. Welded or equivalently secured to the casing bottom and theflange llis an inside 'upstandingcylindrical partition 12, shaped at itslower-end to conjointly' form a seat with the flange 11 for.a gasket 13."The gasket rests upon the aforesaid carburetor flange 2, while thedepending flange 11 circumscribes the carburetonflange, as clearly seenin Fig. 2, when'the cleaner-silencerassembly is mounted in positionover. the upper portion of the carburetor.

Secured to the upper end of the partition 12 is an annular cup-likeshell having a deviated bottom 14 and an outer cylindrical wall 15,forming a container for a cleansingjliquidsuch as crankcase oil for theair cleaning part of 'the structure. The deviated bottom portion of thisshell atits juncture with the partition 12 is also shapedto provideaseat for an annular gasket 16.

"A c over 17"is provided :for the top of the casing, and

secured to the outer rim of this cover by a lock seam 18 orequivalentlyis a depend ing filter holding shell 19, the bottom of whichis turned inwardly and joined to an inner shell20; concentric with theshell 19 but spaced therefrom to *define a compartment therebetween fora filter mass or element 21'0f any-suitable material, such as curledcattle tail hair. 'One or more depending feet 22. are secured tothe-underside of the cover and abut against the curvature upper-endof'the inner shell' 20'to lend stability to the stfllcture andto insurepositive engagement of thefilter holding means with;the gasket16 whenthecover together with the'entire filter-element is positionedon thecasing, the lockseam ofthecover resting on the aforesaid gasket10=atthetopof thecasing. The cover is held in position on' the-casingbymeans-ofa bolt 23 secured to the upper portion of thecarbureto'r, andwhichextends through a suitable aperture in the covertobe engaged by awing nut 24- externally of the-cover.

:T he composite -=fllter-holding shell made up of the elements 19 andhas .enlarged openings in the bottom thereof as indicated -at-25,-andover those openings an internal screen 26 may be'located,-if so desired.This filter holding shell also carries a baflle 27 secured to thebottomthereof,whichbaffle extends down into the liquid containerto meterthe-amount of liquid carried into the filter mass by traveling 'air,during operation.

Theinner-element 20 of the filter holding shell-conjointly :Withfllepartition 12 forms a housing for the upper portion. ofthe carburetor'above the flange 2,-an'd also acts, of course, as the outlet conduitfor clean air. It will also be noted that there is an annular passage 28between the outer element 19 in the filter holding shell and thevertical wall 15 of the liquid cup through which air descends toward theliquid in the bottom of the cup member.

Now it will be noted that the entire interior of the casing comprisingthe portions 5 and 6, outside of the partition 12, the vertical wall 15of the liquid cup, and in the upper portion outside the outer wall 19 ofthe filter holding shell, is all one volume chamber This volume chamberis, as shown, preferably of a size sufiicient for the attenuation of awide band of sound waves of different wave lengths or frequencies. Ofcourse, this volume chamber is in open communication with the annularair inlet passageway 28 leading toward the liquid in the bottom of thecup. In order to tune this large volume chamber to a predeterminedfrequency or narrower band of frequencies, we have provided a simplepartition element 29 in the upper part of the casing, the lower end ofthe element being secured to the inside of the outer casing wall, andthe upper end of the element being secured to the casing adjacent thetop opening. The partition is arcuate in shape and its intermediateportion is disposed opposite an opening in the casing wall in which adirty air inlet duct 30 is mounted. It is not essential that a conduitor duct 30 be utilized, but it is preferable in order to eliminate thepossibility of debris lodging inside the casing, as might be the case ifa bare opening were provided.

The partition 29 therefore forms a double branched tuning tube, or, in amanner of speaking, a pair of tuning tubes or channels extending inopposite directions but having a common junction with the inlet 30. Asseen in Fig. l, in the illustrated embodiment, the branches or separatetuning tubes 31 and 32 formed by the partition 29 are of equal lengthterminating at their open ends 33 and 34, respectively. It is notessential that the branches or tubes 31 and 32 be of equal lengthmeasuring from the center line of the inlet 30, because under certaincircumstances it might be desirable to vary the lengths of these tubesin order to effect a desired tuning of the volume chamber. To that end,in Fig. 1, we have indicated other points of termination such as 33a forthe tube 31, and 34a for the tube 32, in which event the tube 31 wouldbe noticeably longer than the tube 32. The tubes or branches 31 and 32may be shortened as much as desired, and lengthened substantially asmuch as desired, it being only necessary that there be room between theopen ends 33 and 34 of the tubes to discharge the proper amount ofincoming air and without interference or turbulence between the airstreams. But only in rare cases will it be necessary for the tubes topass beyond the diametral plane through the bolt 23 which is the centerof the air cleaning structure since there is a tremendously widevariance of frequencies for the volume chamber that may be acquired withtubes of less length.

It should be especially noted that with the instant arrangement adequatetuning of a volume chamber incorporated in an air cleaner-intakesilencer assembly of the character that fits over the upper portion of acarburetor, is provided by way of the tuning tubes or branches 31 and32, and no increase in overall size of the casing is necessary, sincethese tubes are inside the volume chamber itself.

Now in operation, incoming dirty air enters the inlet 30, substantiallydivides itself into two streams passing through the tubes 31 and 32, anddischarges directly into the volume chamber. The air descends throughthe annular passage 28, contacts liquid in the bottom 14 of the liquidcup member, passes upwardly through the filter mass 21, and enters in aclean and dry condition inside the enclosure formed by the inner wall 20of the filter shell and .the partition 12, whereupon the air may enterthe carburetor directly in the region of the opening or openingscontrolled by a choke valve. Noises emanating from the engine will exitthrough the opening or openings controlled by a choke valve, passreversely through the filter element and the sound waves upon reachingthe bottom of the passage 28 will be in communication with the tunedvolume chamber. The structure of the instant invention is such thatsound frequencies over a relatively wide range will be attenuated withthe volume chamber tuned for a single frequency. For example, if thevolume chamber is tuned to a frequency of 98 cycles per second, it hasbeen found that it effectively silences any sound emanating from theengine and having a frequency between 103 and cycles per second. Thus,it will readily be seen that the same cleaner-silencer assembly may beused on several different automotive engines, without even a minorchange therein.

At present, one theory of operation of the instant invention is that thedouble-branched tuning tube or channel forms an acoustical short circuitfor the volume chamber, in that the impedance to sound waves at the airinlet opening is far greater than the impedance to sound waves in adirection from one tube branch into the other. Tests have not definitelyproven this theory correct, but conversely have indicated no real errorin it.

In most cases the main sound to be attenuated is the fundamental enginetone, commonly referred to as power roar. With the volume chamber tunedto attenuate or neutralize that particular tone, it will automaticallyneutralize one or more harmonics thereof, as well as other tones withina reasonable range on either side of the frequency of that tone, and inthe case of the instant invention, that range is definitely Wider thanwith any resonator attenuating chamber heretofore known. Thatfundamental engine tone is to be distinguished from the rather sibilanthissing noise of suction in the engine, which hissing noise iseffectively eliminated or absorbed by the filter element 21 itselfwhich, in the case of the instant invention, accomplishes the sameresult as hiss pads heretofore used inside the cover of the casing. Butwith the instant invention, that hiss pad inside the cover may beeliminated since with the sound waves directed reversely through thefilter element, the filter element performs that additional function.

By way of example, and not by way of limitation, it may be mentionedthat with a cleaner-silencer assembly as seen in Figs. 1 and 2, andhaving an overall longer diameter of 16 inches, exclusive of the inletduct 30, a tuning tube of a 25 inch length symmetrically mounted Withrespect to the inlet, that is to provide two oppositely disposed tubes12 /2 inches each in length effectively tuned the entire volume chamberto a frequency of 98 cycles per second.

Now the tuning of the volume chamber may also be effected by shiftingthe tuning channel or strictly speaking shifting the position of thepartition 29 so as to render it unsymmetrical with respect to the inlet.In this regard, by Way of example, for the same assembly a 25 inchchannel was arranged unsymmetrically, and it tuned the volume chamber toa frequency of 107 cycles per second, so that by merely making thechannel unsymmetrical, the frequency was varied from 98 to 107 cyclesper second. There is another important feature that should be carefullynoted in connection with the instant invention. That is that the volumechamber may be tuned to two widely different frequencies. Again, by wayof example and not by way of limitation, it was noted that the 25 inchchannel arranged unsymmetrically not only tuned the volume chamber to afrequency of 107 cycles per second, but also brought in an additionaldefinite tuning to a frequency of 295 cycles per second. It was furtherfound that with this particular size assembly complete removal of thepartition 29 resulted in the chamber being tuned to 133 cycles persecond and also to a second frequency of 310. When the channel was 18inches in length, symmetrically arranged, thereby providing two tuningtubes of 9 inches each, the chamber was found to be ll l diQl,..Q $.P99. l and, a s ond. tre eacy otjzes; anda.. ZHiI hQha meL symm tistfiisa l uni drthe chamber tit-. 92. cysl sr r .Q nd.aeqi .nd frequencyof 260. v A 6 inch channel symmetrically arranged .andopen at both ends,as were all the other tests, tuned. the volume chamber to 112 cycles.per secontijwith a second frequencyof 2 62,,cyclesper second.

It will therefore b e'.especially inoted thatlwhen necessary, andmanyengines give forth. two;relative1y 'posit ive tones .at widely'spaced frequencies;thegsingle volurne chamber may betuned 'toneutralize. shund waves oftwo widely. spaced frequencieslatthejsametirne." -That .is a very valuable attribute of ,the instantntion because in the past difiiculty has been experiencedflw th lso nesilencers having true resonator chalhibrgbecaus where the resonatorchamber was effective to attenuate the predominantlenginetone, anothersecondary tone then became noticeable.

Now it will be noted that inorder to efiect adequate tuning of thevolumechamber it is simplylnecessary. to either vary the length or,shift theposition of the partition 29, a mosteconornica l procedureinthecourse oi manufacture of the assembly.

Tests were alsomade with one end of: the tuning channelblocked, andwhile vthistuned the.volume chamber properly to a desired frequency orfrequencies, it tends to raise the restriction ofQthe apparatus toentering air. This is indicative of the fact that a tuning channel withbothends open is .mOre desi abIe but not absolutely essential.

In Fig. 3. we have illustrated aslightly different form of constructionwhich may b'e desirable where a little less volume in the attenuatingchamber is desired, and a structure which is-somewhat moreeconom-icalthanthat seen in Figs. 1 and 2. in this instance, the structure is thesame as above described except for. two minor variations. The firstvariation is in the fact that the bafiie 27 andlower part of the filterholding shell are arranged to carry the gasket 16, and thelbottom 14 oftheliq uid cup-is brought inwardly and curved upwardly as indicated at35 to bear against that gasket. The second variation'is'the eliminationof the partition 12, and the substitution of afsloping partition 36.which is. spot welded or equivalently secured to an intermediateportionof thebrottom 14 of the oil cup at its upperend, and at it'slowerend is secured to .the overalhcasingbottom adjacent the point where thatcasing bottorn is shapedto accommodate the gasket 13. Thestructuredisclosed in Fig. 3 operates in all respects" identical withthe. structure shown irrFigs. 1 and 2, with the single exception thatthe volume of the attenuating chamber is slightly reduced owing to thedilferent shape of the partition 36 frornth'atof the partition 12.

In Figs 4 and 5 we have illustrated ajorm of construction thatdiffers-from that previously disclosed irrthat the tuning channels ortubes. are disposed on the, outside of the main casing, and also by..thefactthat in servicing the air cleaner, the top together with. the,filter element may first be removed, then treliquid a cup lifted out ofthe main casing whichmay remain in position on the flange of thecarburetor. In this instance, theupper portion 6 of the casing is solidopposite the inlet duct 30 as indicated at 37. A channel-shaped member38 is secured to the outside'of the casing wall to form the opposedtuning channels, and in an intermediate point that channel is providedwith a flanged opening as indicated at 39 to receive the inlet, ductiii.The ends of the side branches 4t) and 41 of the tuning tube member 38communicate with the interior of the casing by way of elongated slots 42(Fig. 5) cut in the wall of the upper casing portion 6, both ends of thechannel member 33 itself being externally closed as indicated ate} inFig. 4. As was the case with the embodiment described in coninectionwith figs. 1 and 2 it is not essential that the tubes or branches'4t}and 41 be'of'the same length, but

theynmy terminate at difierent portions, as indicatively th ws tfiti tdl li ss i ni i .tj t Pai e sou 1 or at ethetroint dpendingyroe D nielrquen siredi or, he

In" this instance, also, the gasket 16 upon which the filter holdingshell seats, is held by aformatio'nin the A n0tthe;b ttom-,1 4ofrthefliquid cup as described'in. 'nnectionwith Fig; '2, but there isno. vertical partition 12. L lnlieiivthereof; therehis asl opingpartition 44 secured in twopla cestto the bottom .14 of the liquid cupas indicated at 4 5. and toinsure adequatestrength and rigidity .Thelower portion of this partition is chanholed inwa rdly to hold'an agaist gasket 41 which seats against th bat e s ithas nau s e pa ti o 44 m nte i aflat s r3 1d n d w w y W t e se t; fo the ske 3. f rm n the casingbottom, but is notseeured .tqthe casing bottom.

A prsiin ynw mth slea e nfF sand 5 i to be serviced, it is a simple expedient to remove the wingnut -24, lift off the eovmyl'l c arrying thefilter unit..therewith, then-lift out the-liquid .cup 14-15 togetherwith the partition 44. and gasket47, leaving .thecasing proper seatedonthegfiangel. of. the c arburetor.. .With. this arrangement it is simplerto empty the cleasisingliquid and accumulated .dirt from the liquid.cup,.. refill it. with. .new cleansing liquid replace it, and set..thecover with the filterunitin..position,\.then tighten down the wing nut24. to clamp' all..parts firmly in place and in sealing engagement witheach other. T Otherwise-the.structureoffigs. 4' and 5, insofar as soundattenuation isconcerned, -iunctions the same asstructurespreviously,described;'It' will be noted, also, 1hat---the-disposition of the tuning tube on the outside of the; casing, ratherthan Qin'side, adds hut a negligible amount to theoverall size of theentireassembly.

- ln 'Fig-w'e have illustrated'a still different form of structure whichaybe more convenientfo r certain installations; but which functionsinsofar;as airicle aning andsilencing ste med are same manner fa s thestructure seen in-jh igs. land 2; 7 l-lowevenijn this instance ent pp rpo o of. t e re i s fr mo a e al with theqfilter element of th rfcleaner when servicing is needed To end, it will benoted that the uppermarginal part of the lowerportion 5 of the casing is channeled asindicated z t-48 to forrn a seat for a gasket 49, which .ga sket andchanneling extend entirely, around this lower portionof thecasing. Theupper portion of the casing, here designated oa, has integral with it acover portion Edgar-id ithis gupper po'r'tion is not lock seamedto,thejower portion, but the lower edge of the' uppenportion ani's-froll'ed orbeaded as at 50 entirely ,therearound to seat onthegasket 49. The outer wall 19 of the filter holdingshell is spot weldedor equivalently secured tothe inside of the top part. of the upperportion 6a, rather thanheing were amed to theseparate cover 17 describedinfcohnectiori .wi tli Figs. 1 and 2.

v:With thefarr aiigemerit: of :Fig l 6, when servicing is reiq retileaihe .u n inl t ltisfr m v t e entire upp portion; of the overallcasir gis lifted off the gasket 49, carrying the entire filterelementtherewith; The lower portion 5 of the icasing may then be lifted otf thecarburetor flange Zandthe dirty liquid dumped from the liquid cup 1415.Preferably, the air inletduct 30 is c'arriedby the upper portion 6a ofthe overall casing.

.Whilean air cleaner-silencerassembly constructed in various .siz'esandinhccordaneewithone ofthe structures hereinbefore explained ishighlyefficient and satisfactory ior cleaning incoming air and effecting:intake silencingfor substantially any internal combustion engine, oneunusually rare and unique situation with a particular automobile enginehas been noted. "All'atternpts toiefiectively" silence that particularengine by silencingimeans heretofore known and made infa size to fit the'allowable space proved inetfective until Ltheadventof the instantasaasas invention. The explanation for the distinctly and curiouslypeculiar sound production from this individual engine appears to be thatthe engine developed a relatively deep tone other than the fundamentaltone, and that the intake manifold, providing a constant volume, wasinadvertently and unintentionally constructed so as to be tuned to thisother tone and function as a Helmholtz amplifying resonator upon theopening of the intake valve to a cylinder. Such unexpected amplificationof the second engine tone, in effect made that tone the predominant one,and it obviously would be particularly significant when the fundamentaltone was silenced. Whether or not that second amplified tone was of thefrequency sufficiently close to the fundamental tone to be effectivelyattenuated by any of the structures illustrated in Figs. 1 to 6,inclusive, is of no moment, since the unexpected strengthening of thetone by amplification apparently rendered it irresistible to jointsilencing along with the fundamental tone.

However, even this singular but objectionable phenomenon was effectivelyovercome by a slight modification of the instant invention, illustratedin Fig. 7. The general structure is substantially the same as shown inFigs. 1 and 2. In this instance, however, there is an added partition 52which has a marginal portion secured in the lock seam 7 entirely aroundthe casing, and the inner marginal portion spot welded or equivalentlysecured to the wall 15 of the liquid cup 14-15, as indicated at 53. Thispartition, therefore, effectively divides the lower portion of theoverall volume chamber into a separate true resonator chamber 54 which,in the illustrated instance, comprises all of the contents of the lowerportion of the casing, and a part of the volume within the upper portion6. The resonator chamber 54 is acoustically coupled to the path of soundwaves emanating from the engine through the carburetor by means of aseries of apertures or openings 55 in a partition 12a which correspondsto the partition 12 described in connection with Pig. 2, but which inthis instance has an outwardly turned margin secured to the bottom ofthe casing. Preferably, a tuning skirt 56 is also utilized to define apassageway 57 between itself and the partition 12a, the tuning skirtbeing concentric with the partition 12a, but having a flared upper endso that it may be secured to the wall 12a at the top. The lower end ofthe tuning skirt or tube 56 is merely open. Varying the width of thepassage 57 and lengthening or shortening the skirt or tube 56 effectsdesirable tuning for the resonator chamber 54.

With this arrangement, the amplified tone emanating from the engine isat once attenuated by the resonator chamber 54, and the sound waves ofthis tone do not reach the filter element 21 and ultimately the mainvolume chamber in the upper part of the casing. The main volume chamberabove the partition 52 attenuates other tones from the engine and istuned by the branched tuning tube formed with the partition 29, in thesame manner as above described in connection with the showing in Figs. 1and 2.

From the foregoing it is apparent that we have provided an aircleaner-intake silencer assembly of a character that will house orreceive therein the major portion of the carburetor, and yet which maybe effectively, easily, and economically tuned over a great range ofsound frequencies without altering the overall dimensions of thestructure. Further, it will be apparent that we have provided an intakesilencer of a new type which attenuates a greater range of soundfrequencies upon a single tuning than was heretofore possible, and whichalso may be tuned to more than one sound wave having frequencies widelyapart. The instant invention also eliminates the need of the hiss padsformerly used inside the covers of silencer or air cleaner arrangements,and effectively and economically, by a simple change in construction,may be made to neutralize or attenuate even it) totally unexpectedengine noises. The entire assembly is even more economical thanassemblies of similar character heretofore known, possesses many moreadvantages, is highly durable, and easily installed and serviced.

It will be understood that modifications and variations may be elfectedwithout departing from the scope of the novel concepts of the presentinvention.

We claim as our invention:

1. An air cleaner and intake silencer assembly, including a casinghaving a clean air outlet opening through which sound waves to beattenuated enter the casing, air cleaning means in said casing, meanssealing off said outlet opening except by way of a path through said aircleaning means, said casing extending laterally well beyond said aircleaning means to define a volume attenuating chamber disposedsubstantially around said air cleaning means and sized for theattenuation of sound waves of dilferent frequencies, said casing havingan inlet opening, and tuning tube branches communicating with andextending both ways from said inlet opening with their outer endsopening into said chamber, incoming air passing through said tubebranches, said branches being sized to tune said chamber for attenuationof a predetermined range of sound frequencies.

2. An air cleaner and intake silencer assembly, including a casinghaving a clean air outlet opening through which sound waves to beattenuated enter the casing, air cleaning means in said casing, meanssealing off said outlet opening except by way of a path through said aircleaning means, said casing extending laterally well beyond said aircleaning means to define a volume attenuating chamber disposedsubstantially around said air cleaning means sized for the attenuationof sound waves of diiferent frequencies, said casing having an inletopening, and a plurality of tuning tubes for said chamber carried bysaid casing, said inlet opening leading to said tuning tubes only, andthe free ends of said tubes opening into said chamber, said tubes beingsized to tune said chamber for the attenuation of sound waves of apredetermined range of frequencies.

3. An air cleaner and intake silencer assembly, including a casinghaving a clean air outlet opening through which sound waves to beattenuated enter the casing, air cleaning means in said casing, meanssealing olf said outlet opening except by way of a path through said aircleaning means, said casing extending laterally well beyond said aircleaning means to define a volume attenuating chamber disposedsubstantially around said air cleaning means sized for the attenuationof sound waves of difierent frequencies, a channel shaped member securedto the wall of said casing to define with said wall a tuning tube forsaid chamber with both ends thereof opening into said chamber, and saidcasing having an inlet for contaminated air which opens into anintermediate part of said tuning tube, said tuning tube being sized totune said chamber for the attenuation of a predetermined range of soundwaves.

4. In an air cleaner and intake silencer assembly, a casing having anair outlet opening in the bottom of a size to receive the upper portionof a carburetor, said casing having an opening in the top thereof, aremovable cover for said top opening, annular air cleaning means beneathsaid cover, means sealing off said outlet opening except to air passingthrough said cleaning means, said casing defining therein a volume soundattenuating chamber in open communication with said cleaning means andsized for the attenuation of sound waves of different frequencies, atuning tube for said chamber carried by the casing and extending alongthe wall of said casing a predetermined distance and opening into saidchamber, and said casing having an air inlet opening into anintermediate part of said tube, said tube tuning said volume chamber fora predetermined range of sound frequencies.

5. An air cleaner and intake silencer assembly, comprising a casingenclosing a volume chamber sized for attenuating a relatively widebandof sound waves, said casing having an air inlet opening and an unimpededair outlet opening,. means defining a path of travel; for

air 'through the casing, filter means in said path, said E'path and saidfilter means communicating directly with {and said path forming a partof said volume chamber inside said casing, said path definingmeansincluding tuning tube means carried by said casing and communicatingdirectly with said air inlet opening at an intermediate point andextending both ways therefrom with the ends thereof opening freely intosaid chamber, said tuning tube means being sized to tune said chamberfor the attenuation of a predetermined narrower band of sound waves.

6. An air cleaner and intake silencer assembly, comprising a casingenclosing a volume chamber of predetermined size relatively to soundwaves to be attenuated therein, air cleaningmeans in said casing, saidcaslng communicating abruptly with the confronting ends of saidchannels.

7. An air cleaner and intake silencer assembly, comprising a casingenclosing a volume chamber of a predetermined size relatively to soundwaves to be attenuated therein, air cleaning means in said casing, saidcasing -having a free and unrestricted outlet opening for clean airleading from said air cleaning means and through -which sound waves tobe attenuated enter said volume chamber, means carried by said casingdefining a doublebranched tube open at the free ends for free andunimpeded communication with said chamber, and said casing having an airinlet opening abruptly into the junction of the tube branches at anangle exceeding 45 between the axis of the inlet and the axis of thetube, whereby the impedance to passage of sound waves outwardly throughsaid air inlet is far greater than the impedance in a direction from onebranch ofsaidtube toward the other.

'8. An air cleaner and intake, silencer assembly,- comprising a casingenclosing a volume .chamber sized for the attenuation of a relativelywide band of sound .waves of different frequencies, said casing havingan air inlet -opening and anair outlet opening, air cleaningmeansincludinga filter in said casing, meanssealing offsaid outlet openingexcept by way of a path through said air cleaning means, said pathcommunicating directly with'said volume chamber inside said casing, andtuning tubes carried bygsaid casing and communicating with andextending. both ways along the casing wall from-said inlet opening withtheir separated ends opening into said chamber, said tubes being sizedto tune said volume chamber forthe attenuation of a predeterminednarrower band of sound Waves.

9. An air cleaner and intake silencer assembly, comprising acasingenclosing a volume chamber sized for the attenuation of a relativelywide band of sound Waves of different frequencies, said casing having anair inlet opening and an air outlet opening, air cleaning meansincluding a filter in said. casing, means scaling 015? said outletopening except by Way of a. path through said air cleaning means, saidpath communicating directly with .said volume chamber inside saidcasing, and means connected to the wall of said casing defining achannel in 'open communication with and extending sidewise both waysfrornsaid inlet opening with the ends of the channel I. 1 opening. intosaid volume chamber, said channel be1ng of .a device needing an airsupply, comprising a casing defining av volume chamber therein sized forthe attenua= tion of a predetermined relatively wide band of soundwaves, said casing having an opening for the discharge of air andthrough which sound waves from the device enter the casing, and a tuningtube carriedby said casing with both ends thereof opening into saidchamber, 'said casinghaving an air intake openingleading 1nto anintermediate partof said tube, and said tube be1ng other- 15 wiseimperforate and sized to tune said chamber for the attenuation ofa,predetermined narrower band of sound wavesysaidtube, being longer on oneside of said air volume attenuating chamber With which said air clean- 7ing means are in open communication and which chamber is sized toattenuate a predetermined relativelywide band of sound waves, tuningmeans for said chamber 7 carried by said casing and sized to tune saidchamber for the attenuation of a predetermined narrower band 7 of soundwaves, said tuning means forming a flow passage open at both ends andentirely independent of said chamber, and said casing having an inletfor contami- ;nated air opening directly into the flow passage formed bysaid tuning means intermediate the ends thereof.

12. An intake silencer for connection with the intake of a deviceneeding an air supply, comprising a casing .defining a volume chambertherein sized for the at- .tenuation of a predetermined relatively Wideband of sound waves, said casing having an opening for the discharge ofair and through which sound waves from the device enter the casing, atuning tube carried by said casing with both ends thereof opening intosaid chamber,

said casing having an air intake opening leading into an .intermediatepart of said tube, and said tube being other- WlSB imperforate and sizedto tune said chamber for the attenuation of a predetermined narrowerband of sound waves, said casing being cylindrical, and said tuning tubebeing longitudinally curvate to follow the, curvature of the cylindricalcasing withradii from the open ends of 50 the tube defining an angle ofat least which, angle includes the tube itself.

13. An intake silencer for the intake of a device requiring an airsupply comprising a casing having an air inlet opening in the wallthereof, said casing enclosing a volume chamber of; sufiicientsize forthe, attenuation of arelatively Wide band ofwsound. waves, partitionmeans,in said casing defining withthe inside of'the casing Wall tuningchannels opening freely into said volume ;chamber and extending inopposite directions ina lateral plane from saidinletopening andincommunication with said inlet opening, the adjacent: ends. ofsaid-channels ,confronting each other at saidinlet opening to in effect-and conjointly define a path fortsound waves substantially atrightangles to-theair path through said inlet opening, saidchannelsbeing sized to tune said volume chamtrance of sound waves to beattenuated.

'14; An intake silencer for connection with the air intake. of aninternal combustion engine, comprising a casing enclosing a-volumeattenuating chamber of sufiicientrsize for the attenuation of arelatively wide band of, sound waves, said casing having an airinletopening, and tuning means communicating at a point intermediate the endsthereof with said opening and defining flow passages for incoming airextending in different directions from said opening, said flow passagesopening freely and unimpeded into said'volume chamber, said flowpassages being sized to tune said volume chamber for the attenuation ofa narrower band of sound waves, said casing having an unimpeded outletopening for the discharge of air and through which sound waves to beattenuated enter the casing in opposition to the direction of travel ofair, and connecting means to connect the silencer with the air intake ofan engine with said outlet opening communicating with the opening in theengine air intake.

15. An air cleaner and intake silencer unit, comprising a casing havinga clean air outlet opening and through which sound waves to beattenuated enter the casing, air cleaning means in said casingcommunicating with said outlet opening, said casing defining an interiorvolume attenuating chamber with which said air cleaning means are inopen communication and which chamber is sized to attenuate apredetermined relatively wide band of sound waves, tuning means for saidchamber carried by said casing and sized to tune said chamber for theattenuation of a predetermined narrower band of sound waves, said tuningmeans forming a flow passage entirely independent of said volume chamberand with both ends communicating with said chamber, and said casinghaving an inlet for contaminated air opening directly into the flowpassage formed by said tuning means intermediate the ends thereof, andmeans cooperating with said casing to define a resonator chamber inaddition to said volume chamber, said resonator chamber having anacoustic coupling to permit entry of sound waves entering said casing.

16. An intake silencer for association with the intake of a deviceneeding an air supply, comprising a casing having an air outlet openingand an air inlet opening spaced therefrom, said casing defining a volumeattenuating chamber therein in open communication with said openings andsized for the attenuation of sound waves of different frequencies, aconduit extending into said casing around said outlet opening, means insaid casing defining a flow path for outgoing air through said conduit,and partition means in said casing cooperating therewith in defining andsealing off a resonator chamber around said conduit which is closedexcept for an acoustic coupling between the path through said conduitand said resonator chamber, and tuning tube means carried by said casingfor said volume chamber.

17. An intake silencer for association with the intake of a deviceneeding an air supply, comprising a casing having an air outlet openingand an air inlet opening spaced therefrom, said casing defining a volumeattenuating chamber therein in open communication with said openings andsized for the attenuation of sound waves of different frequencies, aconduit extending int-o said casing around said outlet opening, means insaid casing defining a flow path for outgoing air through said conduit,partition means in said casing cooperating therewith in defining andsealing off a resonator chamber around said conduit which is closedexcept for an opening in the wall of said conduit to establish anacoustic coupling with said resonator chamber, a tuning tube for saidresonator chamber concentric with said conduit, and tuning means carriedby said casing for said volume chamber.

18. An intake silencer for association with the intake of a deviceneeding an air supply, comprising a casing having an air outlet openingand an air inlet opening spaced therefrom, said casing defining a volumeattenuating chamber therein in open communication with said openingssized for the attenuation of sound waves of difierent frequencies, aconduit extending into said casing around said outlet opening, means insaid casing defining a flow path for outgoing air through said conduit,partition means in said casing cooperating therewith in defining andsealing off a resonator chamber around said conduit which is closedexcept for an acoustic coupling between the path through said conduitand said resonator chamber, a tuning tube for said resonator chamberconcentric with said conduit adjacent said acoustic coupling, and tuningmeans carried by said casing for said volume chamber.

19. In an oil bath air cleaner assembly a housing en-- closing an oilsump and filter element, an annular inlet in the housing for dirty air,a silencer chamber surrounding the housing and enclosing the annularinlet, an air inlet orifice in the silencer chamber, a partition in thesilencer chamber masking the inlet orifice nad extending a substantialdistance on each side of it to provide arcuate tuning tubes, and anoutlet in the assembly for clean air.

2-0. in a hat type oil bath air cleaner, an annular housing having anoil sump and filter element concentrically disposed therein, an annularinlet formed in the housing so that dirty air may communicate with theoil sump and filter element, an outlet formed in the housing for cleanair, an annular silencer chamber surrounding the housing, the annularair inlet opening into the silencer chamber, the housing forming anannular depression in the silencer chamber, an inlet orifice for thesilencer chamher, and inlet tuning channels leading from the inletorifice a predetermined distance along the sides of the silencerchamber.

21. In a liquid bath hat-type air cleaner and silencer assembly, afilter housing enclosing a liquid sump and a filter medium, an annularinlet in the filter housing for dirty air in communication with theliquid sump and filter medium, a silencer housing around the filterhousing defining a silencer chamber with it, the annular inlet in thefilter housing for dirty air opening into the silencer chamber, an airinlet orifice on the side of the silencer housing opening into thesilencer chamber to provide for the dew of dirty air through thesilencer chamber to the annular inlet in the filter housing, an outletin the assembly for clean air in communication with the filter medium,and an arcuate partition in the silencer chamber conforming generally tothe inner surface of the silencer housing and masking the inlet orificein the side of the silencer housing, the arcuate partition extending asubstantial arcuate distance on each side of the inlet orifice andproviding inlet tuning tubes leading from the inlet orifice apredetermined distance around each side of the silencer housing openinginto the silencer chamber generally on opposite sides of the filterhousing.

22. In a liquid bath air cleaner assembly, a filter housing enclosing aliquid sump and a filter medium, an annular inlet in the housing fordirty air, an outlet in the housing for clean air, a silencer chamberaround the housing enclosing the annular inlet, and tuning passagesaround the wall of the silencer chamber of a predetermined length incommunication with the outside and opening into the silencer chamber,the tuning passages being generally arcuate and conforming generally tothe silencer chamber.

References Cited in the file of this patent UNITED STATES PATENTS

